A time-of-flight (TOF) camera is a range imaging camera system that resolves distance based on the speed of light, measuring the time-of-flight of a light signal between the camera and the subject for each point of the image. With a time-of-flight camera, the entire scene is captured with each laser or light pulse. Time-of-flight camera products have become popular as the semiconductor devices became fast to support such applications. Direct Time-of-Flight imaging systems measure the direct time-of-flight required for a single laser pulse to leave the camera and reflect back onto the focal plane array. The 3D images can capture complete spatial and temporal data, recording full 3D scenes with a single laser pulse. This allows rapid acquisition and real-time processing of scene information, leading to a wide range of applications. These applications include automotive applications, human-machine interfaces and gaming, measurement and machine vision, industrial and surveillance measurements, and robotics, etc.
The simplest version of a time-of-flight camera uses light pulses or a single light pulse. The illumination is switched on for a short time, the resulting light pulse illuminates the scene and is reflected by the objects in the field of view. The camera lens gathers the reflected light and images it onto the sensor or focal plane array. The time delay between the out-going light and the return light is the time-of-flight, which can be used with the speed of light to determine the distance. A more sophisticated TOF depth measurement can be carried by illuminating the object or scene with light pulses using a sequence of temporal windows and applying a convolution process to the optical signal received at the sensor.